The earliest recorded use of magnetism as a method for a divination effect is probably “Les trois nombres magiques”, which appears in the second edition of volume one of Edmé-Gilles Guyot's Nouvelles recreations physiques et mathematiques, 1772, p. 147. A set of numbered wooden blocks is arranged and hidden in a wooden box by a spectator. The order is determined by the performer, who does not touch the box but observes it by looking through a small telescope. The telescope contains a compass, which points in four different directions depending on which numbered block it is near.
Much the same effect, with a more elaborate method that also uses magnetism, is “The Box of Divination” in volume two of W. Hooper's Rational Recreations, 1774, p. 252 of the second edition.
By the end of the nineteenth century, the trick (in streamlined form) is well established. A version appears as “The Box of Numbers” in Professor Hoffmann's More Magic, 1890, p. 257. In this, the pieces are defined as “slabs” (hence closer to thick cards or tablets rather than cubes). The same effect is recycled in William J. Hilliar's Modern Magician's Hand Book, 1902, p. 222.
In the January 1899 issue of Mahatma, Vol. 2 No. 7, p. 190, Henry Hardin has “A Clever Improvement” with the introductory comment: “The box of numbers trick, with the magnets and compasses, will be remembered by all who are to any degree proficient in legerdemain….” (Hardin's trick does not use magnets.)
Actual playing cards show up in “Mysterious Card Trick” as an item in Pierce's Magic World, Vol. 6 No. 9, Dec. 1922, p. 130, in the monthly “Home Made Magic” column written pseudonymously by “Thumb Print” (identity unknown).
The commonness of the basic trick is evidenced by it being the first item in the first installment of Dunninger's “Magic For Everybody” series in Science & Invention, 1923, a magazine for the public. This is a simplified version, described for the lay reader. Titled “The Blocks of the Yogi”, it uses plaques that are much closer to cards than cubes.
A significant departure from blocks or plaques (but rather coins and envelopes) was devised in 1935 by Stewart James. He performed this at that year's Abbott's Get-Together and won the Originality Contest. Later that year, he marketed it as “Numismatigic” and a year later, having apparently sold few if any, gave it to Annemann who published it in The Jinx, No. 25, p. 157, that October.
“The Wooden Block Divination Trick” appears in John Northern Hilliard's Greater Magic, 1938, p. 856, along with a variation using colored candles. An untitled “slab” version leads off the section on divination in Henry Hay's Cyclopedia of Magic, 1949, p. 180.
In 1958, Dr. Jaks released “Mental Touch”, which used shimmed cards. In the same year, Corinda published the first installment of 13 Steps to Mentalism, p. 136, which includes Punx's “The Magnetic Blindfold” that incorporates shimmed cards as well.